In recreational vehicles, space is at a premium and dictates the use of extremely compact appliances, utilities as well as built-in furniture to serve the needs of the occupants. Accordingly, anything that can be done to eliminate appliances or to permit appliances to serve a dual purpose is extremely important insofar as space conservation is concerned. In many climates, such as, the Southwestern region of the United States, temperatures do not drop so drastically as to require a separate furnace installation. Nevertheless, there are times when the temperature drop is such that a space heating source is necessary to maintain the temperature at a comfortable level, particularly at night.
In the past, it has been proposed to utilize the burners on a cookstove for space heating purposes and various attachments have been devised to this end. For example, U.S. Pat. No. 2,553,278 to H. R. Rogant employs a unit which can be placed on a stove and directly over the burners for space heating purposes but requires a fan or blower which is controlled by a thermostat to turn on only when the temperature level in the unit drops below a predetermined temperature. U.S. Pat. No. 530,640 to J. Guy also discloses a heating attachment for gas cooking stoves including a pair of tubes which will connect into a common outlet or discharge; also, U.S. Pat. No. 321,400 to L. W. Turner discloses a heating unit which can be placed over the burner opening in the stove and has a discharge pipe that will connect up to a stack or other exhaust pipe. U.S. Pat. No. 2,088,280 to A. Schillinger also discloses a stove heating attachment in which a tubular section referred to as a back wall forms a channel for the passage of cool air to mix with hot gases from a discharge opening, and a flue pipe extends vertically through the center of the unit. Other representative patents are U.S. Pat. Nos. 1,402,728 to J. Cassady, 1,624,089 to F. D. Sullivan, 3,280,813 to G. N. Schaenzer, 3,509,869 to E. L. Woods, and 4,425,901 to G. Callison.
In the design and construction of heating units of the type described, it is important that the unit be accurately centered over the burners or other source of heated air so as to confine the upward movement of the heated air and fumes to the interior of the housing and, through an exhaust duct, to the exterior of the vehicle; also, that the air to be heated be drawn through the housing in such a manner as to absorb a maximum amount of heat from the interior of the housing and without any tendency to draw the fumes from the burner or other heat source out of the housing and into the room.